Today biodiesel is made by the batch, a naturally less efficient way for processes to run. A continuous process would be less expensive to run, easier to manage and need less storage and product movement both in front and at the finished side. Continuous biodiesel production would get less expensive, more competitive and become more consumer friendly. Most of the technology would apply to jet fuel production as well. It’s an important and worthwhile research effort.
More bio oil is coming, too. While many still bemoan corn-based ethanol, China has caught on and is importing corn dried distillers grain (what’s left over after the corn starch is made into ethanol) from the U.S. for meat production. The ethanol industry in the U.S. has realized there is excess corn oil in the distillers grain and is moving rapidly to get the oil out and add it to the biofuel market. Cutting back on the oil in the distillers grain makes it a better feed for most meat animals.
Meanwhile around the world other crops are producing ever more bio oil destined for the biodiesel or bio jet fuel markets. When France’s Centre National de la Recherche Scientifique (CNRS) announced that its Centre de Recherches Paul Pascal (CRPP) developed a novel catalyst capable of continuous production of biodiesel, heads turned and serious news and blogs worldwide are taking note.
The new catalyst, of which patents are already filed, has just been explored in a paper published in the journal Energy & Environmental Science.
To get to a petroleum product substitute that will function in an open market bio oil needs processed to biodiesel or bio jetfuel. The common bio oils such as oilseed rape, palm, sunflower, cotton and soybean oil become biofuels from a chemical reaction, catalyzed in either an acidic or preferably a basic medium, between the vegetable oil (90%) and an alcohol (10%). This reaction, known as transesterification, converts the mixture into a methyl ester (the main constituent of biodiesel) and glycerol. The glycerol then goes on its own market path.
The reaction has a step where the methyl ester conversion into the corresponding acid salt reduces methyl ester yield. To get across the step of controlling the salt formation certain efficient and selective enzyme based catalysts such as those belonging to the family of lipases (triglyceride hydrolases) are used. But these are expensive and don’t stay together well when used in industrial processes.
Biodiesel Continuous Flow Catalyst
The CRPP team has come up with a much better solution – irreversibly confine the enzymes in porous matrices, thus allowing good accessibility and improve the product flow over them.
Initially the study demonstrated the possibility of efficient catalysis, by developing modified silica-based cellular matrices that make it possible to confine the enzymes in order to obtain exceptional yields for the hydrolysis, esterification and transesterification reactions.
The team’s initial work also shows that unpurified enzymes could be used in the matrices.
The fact that they were unpurified was a first step to significantly reducing the cost of biocatalysts. But, the method did not allow continuous biodiesel production. This obstacle has now been overcome.
The CRPP team has developed a new method that generates the cellular hybrid biocatalyst in place inside a chromotography column. The new approach makes it possible to carry out continuous, unidirectional flow synthesis over long periods, since catalytic activity and ethyl ester production are maintained at high, practically steady levels during a two-month period of time. These results are amongst the best ever obtained in this field.
Two months of continuous flow is very different from losing the enzyme dose in every batch or trying to recover the enzymes from each batch. That’s what is turning heads and making news.
Meanwhile the team is continuing research into solvent-free conversion of triesters, aimed at minimizing waste production and curbing the use of solvents and metals in chemical transformation processes. This work, which is planned to meet current energy and environmental requirements, shows how intensely chemists are working in the public interest, and confirms the importance of integrative chemistry.
The French research looks extremely good and answers a major cost problem facing the substitution of bio oils into the middle distillate range of petroleum products. For diesel and jet fuel markets the processing cost has been an issue for years – while proving market value has successfully touched about every possible base. Driving down processing cost will also open the door to much more subsistent land farming where oil crops thrive better than sugar or starch crops, opening more cash income opportunities for subsistent farmers.
The French news won’t make it to major news or big blogs, but you can bet biodiesel producers are thrilled and eager to see if the research will scale at low cost too. It’s likely in time biodiesel consumers will be thrilled, too.
By. Brian Westenhaus